Plans to build a £1bn reservoir between Wantage and Abingdon have been criticised by Oxfordshire County Council cabinet members.

At County Hall on Tuesday, councillors raised serious concerns about the environmental impact of the proposed development, which would supply 250 million litres of water per day to London, Swindon and Oxfordshire.

Instead, they suggested Thames Water should invest the money in reducing the amount of water it wasted - currently more than 600 million litres per day.

Roger Belson, cabinet member for sustainable development, said Thames Water had a water usage target of 158 litres of water per person per day - 28 litres above Government guidelines.

He said: "If Thames Water agreed Defra's target of 130 litres, we wouldn't need a new reservoir at all."

Charles Shouler, cabinet member for finance, added: "It's the leakage issue that concerns me.

"Twenty-seven per cent of treated water doesn't get to customer.

"It's not a good situation."

The cabinet also considered the findings of a report commissioned by the Group Against Reservoir Development (Gard), which concluded Thames Water's draft Water Resources Management Plan (WRMP) was "highly suspect" and the Abingdon reservoir was the costliest option.

The WRMP sets out how demand for water will balance against demand over the next 25 years.

The cabinet's reluctance to back the reservoir was welcomed by Nick Thompson of Gard.

He said: "I'm certainly very encouraged by the cabinet's views on this proposal.

"We have always said that Thames Water needs to sort out its leakages problems which would make the need for this reservoir unnecessary."